Freepost is a postal service provided by various postal administrations, whereby a person sends mail without affixing postage, and the recipient pays the postage when collecting the mail. Freepost differs from self-addressed stamped envelopes, courtesy reply mail, and metered reply mail in that the recipient of the freepost pays only for those items that are actually received, rather than for all that are distributed. Freepost of preprinted cards issued by businesses is also different from postal stationery sold by postal administrations.

In one use of freepost, a business sends bulk mail to potential customers, the bulk mail including envelopes or postcards that potential customers can return to the business by freepost. In another use, magazines include subscription cards that potential subscribers can return by freepost. In another use, a seller can provide a merchandise return label bearing the appropriate freepost indicia (as described below) to a customer so that the customer can return the item to the seller by freepost upon issuance of a Return Merchandise Authorization.

A non-commercial use would be to return lost items belonging to a business. The item will have printed on the back "if found please return by freepost to <address>". For example, UK's NHS worker's RFID access cards can be returned by freepost if lost & found.

In Australia, freepost is called Reply Paid. Specially printed envelopes maybe used, with the permit holder's address, the words "Reply Paid" with an authorization number. The stamp is replaced by three vertical black stripes and a postal bar code. The permit holder pays the postage plus a fee to the postal authority. The customer may also write the Reply Paid envelope out by hand, which is treated the same as the printed envelopes. The delivery address is printed on the top left hand corner of the envelope. The delivery address may be the same as the postcode.

An important customer could have an RP number the same as the post code and the delivery address PO Box, to minimize errors even more.

To coordinate service with the United States, Canada Post uses the same terminology and the same standards as the USPS (as explained below), with the exception of the use of Canadian Postal codes.

In the United States, the United States Postal Service refers to freepost as business reply mail. A mailer wishing to receive mail by freepost must obtain a business reply permit and design the envelopes, postcards, or labels according to the standards specified by the USPS, including the use of an appropriate FIM B or C code. The address on the envelope, postcard, or label is the same as the address for regular mail, except that the ZIP+4 code is different. In some large cities, business reply mail has its own five-digit ZIP code or codes (e.g., 20077 and 20078 in Washington, D.C.). The envelope or postcard also includes space for the business reply permit number.

In the United Kingdom, Royal Mail offers a variety of services. The most expensive service, Freepost Name, enables a customer to purchase a licence to a name which allows the public to send mail to the organisation free of charge using any envelope, and with the Freepost Name handwritten or printed. Only the licensed name is required on the envelope, not the postal address. In addition, Royal Mail offers a range of business reply services enabling a business to provide their customers with pre-printed envelopes in order to send mail to the business free of charge, including: Freepost Standard, Freepost Plus, Business Reply Standard, Business Reply Plus.